Case
A 27 year old male presents through triage complaining of shortness of breath. After obtaining the EKG shown below, he is taken back to a treatment room. What does the EKG show? Can you make a diagnosis? What are the next steps in management?
A 27 year old male presents through triage complaining of shortness of breath. After obtaining the EKG shown below, he is taken back to a treatment room. What does the EKG show? Can you make a diagnosis? What are the next steps in management?
Vent rate 204 BPM | PR interval * | QRS duration 158 ms | QT/QTc 284/523 ms | P-R-T axes * 124 -54
Background
An EKG is diagnostic only in few circumstances, i.e. STEMI, and always must be taken into the clinical context. However, there are certain EKGs an emergency physician must be able to identify and this is one of them. This EKG shows an irregularly irregular wide complex rhythm with various QRS morphologies and rates approaching 300 beats per minute. These are all clues to the diagnosis. First, there are not many causes of irregularly irregular rhythms, the most common by far being atrial fibrillation, but also multifocal atrial tachycardia and occasionally atrial flutter. Next, there is a wide complex rhythm. This may occur from conduction abnormalities (LBBB, RBBB) or sodium channel blockade (TCA overdose being a classic example). These both are fixed pathologies, and would not be expected to produce QRS complexes with various morphologies. Finally, rates approaching 300 beats per minute cannot be via AV nodal conduction. This must either be through an accessory pathway or from a ventricular focus. (1,2)
Considering the above, this EKG could either be polymorphic ventricular tachycardia or atrial fibrillation with aberrant conduction. However, as discussed AV nodal conduction is not possible, meaning an accessory pathway must be in play.
Diagnosis
Atrial fibrillation in the setting of Wolff-Parkinson-White (WPW) syndrome.
Pathophysiology
Recall that in WPW there is an accessory pathway which allows conduction to bypass the AV node. That is why when the atria are beating up to 500 beats per minute in atrial fibrillation it is able to conduct the produce such a high rate (if there is antidromic conduction, see figure below). Additionally, because of the timing and inconsistent depolarization, there are different QRS complexes seen.
An EKG is diagnostic only in few circumstances, i.e. STEMI, and always must be taken into the clinical context. However, there are certain EKGs an emergency physician must be able to identify and this is one of them. This EKG shows an irregularly irregular wide complex rhythm with various QRS morphologies and rates approaching 300 beats per minute. These are all clues to the diagnosis. First, there are not many causes of irregularly irregular rhythms, the most common by far being atrial fibrillation, but also multifocal atrial tachycardia and occasionally atrial flutter. Next, there is a wide complex rhythm. This may occur from conduction abnormalities (LBBB, RBBB) or sodium channel blockade (TCA overdose being a classic example). These both are fixed pathologies, and would not be expected to produce QRS complexes with various morphologies. Finally, rates approaching 300 beats per minute cannot be via AV nodal conduction. This must either be through an accessory pathway or from a ventricular focus. (1,2)
Considering the above, this EKG could either be polymorphic ventricular tachycardia or atrial fibrillation with aberrant conduction. However, as discussed AV nodal conduction is not possible, meaning an accessory pathway must be in play.
Diagnosis
Atrial fibrillation in the setting of Wolff-Parkinson-White (WPW) syndrome.
Pathophysiology
Recall that in WPW there is an accessory pathway which allows conduction to bypass the AV node. That is why when the atria are beating up to 500 beats per minute in atrial fibrillation it is able to conduct the produce such a high rate (if there is antidromic conduction, see figure below). Additionally, because of the timing and inconsistent depolarization, there are different QRS complexes seen.
AVRT with orthodromic (left) and antidromic (right) AV nodal conduction (2)
Life in the Fast Lane Pre-excitation Syndrome
Life in the Fast Lane Pre-excitation Syndrome
Management
Management depends if the patient is stable or unstable. Unstable patients should undergo emergent synchronized cardioversion at 100 J to 200 J with sedation as appropriate. (1,3) Stable patients can be considered for medical management. However, if the rhythm is unknown, it is always appropriate to treat as ventricular tachycardia and perform cardioversion, regardless of the stability of the patient. If WPW with aberrant conduction is suspected, it is important to avoid AV nodal blocking agents, such as adenosine, beta-blockers or calcium channel blockers, as they may promote conduction through the accessory pathway. This can lead to extremely high conduction rates and cause deterioration to ventriculat fibrillation. (1,3,4)
While the common anti-arrhythmic amiodarone may be thought of as first line, it is actually associated with deterioration to ventricular fibrillation and sudden death. (5-7) Procainamide appears to be safe and effective in atrial fibrillation in WPW, and carries a slightly higher level of recommendation by the American Heart Association in the 2015 ACLS guidelines. (3) Procainamide is also recommended in Tintinalli's Emergency Medicine, 8th edition, as well as in the 2015 guidelines from the American College of Cardiology/American Heart Association/European Society of Cardiology. (1,4) It is dosed at a constant infusion of 20-50 mg/min until end points of hypotension, QRS duration increases by 50%, arrhythmia suppression or a maximum dose of 17 mg/kg is given. Maintenance infusion is 1-4 mg/min. Caution advised in cases of prolonged QT and CHF. (3)
Case Resolution
Your patients was unstable and was successfully cardioverted and had the follow up EKG below. Note the classic findings of WPW of short PR interval and a delta wave.
Management depends if the patient is stable or unstable. Unstable patients should undergo emergent synchronized cardioversion at 100 J to 200 J with sedation as appropriate. (1,3) Stable patients can be considered for medical management. However, if the rhythm is unknown, it is always appropriate to treat as ventricular tachycardia and perform cardioversion, regardless of the stability of the patient. If WPW with aberrant conduction is suspected, it is important to avoid AV nodal blocking agents, such as adenosine, beta-blockers or calcium channel blockers, as they may promote conduction through the accessory pathway. This can lead to extremely high conduction rates and cause deterioration to ventriculat fibrillation. (1,3,4)
While the common anti-arrhythmic amiodarone may be thought of as first line, it is actually associated with deterioration to ventricular fibrillation and sudden death. (5-7) Procainamide appears to be safe and effective in atrial fibrillation in WPW, and carries a slightly higher level of recommendation by the American Heart Association in the 2015 ACLS guidelines. (3) Procainamide is also recommended in Tintinalli's Emergency Medicine, 8th edition, as well as in the 2015 guidelines from the American College of Cardiology/American Heart Association/European Society of Cardiology. (1,4) It is dosed at a constant infusion of 20-50 mg/min until end points of hypotension, QRS duration increases by 50%, arrhythmia suppression or a maximum dose of 17 mg/kg is given. Maintenance infusion is 1-4 mg/min. Caution advised in cases of prolonged QT and CHF. (3)
Case Resolution
Your patients was unstable and was successfully cardioverted and had the follow up EKG below. Note the classic findings of WPW of short PR interval and a delta wave.
Vent rate 57 BPM | PR interval 124 ms | QRS duration 158 ms | QT/QTx 490/476 ms | P-R-T axes 37 108 25
Summary
Recall the findings of atrial fibrillation with WPW
Synchronized cardioversion for unstable and possibly for stable patients
If suspected, procainamide may be a better option than amiodarone
For more, see these great reviews from Life in the Fast Lane and Amal Mattu.
References
Submitted by Dr. Michael Craddick, PGY-2
Recall the findings of atrial fibrillation with WPW
- Wide complete tachycardia
- Irregularly irregular rhythm
- Various QRS morphologies
- Rates near 300 bpm
Synchronized cardioversion for unstable and possibly for stable patients
If suspected, procainamide may be a better option than amiodarone
For more, see these great reviews from Life in the Fast Lane and Amal Mattu.
References
- William Brady TL, Chris Ghaemmaghami. Cardiac Rhythm Disturbances. In: Tintinalli JE, Stapczynskj JS, Ma OJ, Yealy DM, Meckler GD, Cline DM, editor. Tintinalli's Emergency Medicine: A Comprehensive Study Guide. 8th ed. USA: McGraw-Hill Education; 2016.
- Burns E. Wolff-Parkinson-White Syndrome. In: Lane LitF, editor.
- Association AH. Part 7: Adult Advanced Cardiovascular Life Support. 2015.
- Writing Committee M, Page RL, Joglar JA, et al. 2015 ACC/AHA/HRS guideline for the management of adult patients with supraventricular tachycardia: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society. Heart Rhythm. 2016 Apr;13(4):e136-221.
- Tijunelis MA, Herbert ME. Myth: Intravenous amiodarone is safe in patients with atrial fibrillation and Wolff-Parkinson-White syndrome in the emergency department. CJEM. 2005 Jul;7(4):262-5.
- Simonian SM, Lotfipour S, Wall C, Langdorf MI. Challenging the superiority of amiodarone for rate control in Wolff-Parkinson-White and atrial fibrillation. Intern Emerg Med. 2010 Oct;5(5):421-6.
- Tiago Luiz Luz Leiria AM, Rafeal de March Ronsoni, Leonardo Martins Pires, Marcelo Lapa Kruse, Gustavo Glotza de Lima. Ventricular Fibrillation during amiodarone infusion in a patient with Wolff-Parkinson
Submitted by Dr. Michael Craddick, PGY-2
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